1. Field of the Invention
This invention relates to a device for cutting out the vent of a slaughtered bird, comprising an elongated centring pin which is provided with a thickened end portion which can be inserted into the vent; a rotatable cutting element with an axially directed cutting edge, the axis of rotation running parallel to the axis of the centring pin, and the cutting edge being directed to and being movable towards the thickened end portion of the centring pin; and an axially movable positioning element of which the surface facing the thickened end portion of the centring pin is intended for interacting with the thickened end portion of the centring pin to position the vent.
2. Prior Art
A device as described above is known from U.S. Pat. No. 2,943,346. This specification describes a positioning element essentially comprising a hollow tube in which the centring pin is fitted in such a way that the thickened end portion of this pin, a cone, projects from the tube. Further, a partial vacuum is created in the tube by extracting air from it. When the cone is inserted far enough into the vent of a slaughtered bird, the skin around the vent comes into contact with one end of the tube. Due to the partial vacuum in the tube the skin is drawn against the end of the tube in the process. In this way the vent is positioned, and an incision can be made around the vent by means of the cutting element, which is moved in the direction of the thickened end portion of the centring pin. The cutting edge of the cutting element in this case moves away from the end of the tube, and the resulting radially directed forces on the orbicular muscle produce the risk of the orbicular muscle being pulled away from the positioning element. This is extremely undesirable, since in this case feces may come away from the intestine of the bird and can contaminate the meat.
If an attempt is made to overcome this problem by a stronger partial vacuum, there is a risk of the cut-out vent as a result being drawn into the tube and tearing the intestinal wall, again with the undesirable consequence of the contents of the intestine being released in an uncontrolled manner.